Automatic cut-out for heating circuits



2:; 1927. l Oct o. PLETscHER, JR

AUTOMATIC CUT-GUT FOR HEATING CIRCUITS original Filed Dec. 4. 1924Patented Oct. 25, i927.

untreuer-Aras 1,546,835 rar-snr erstes.

. 'orTo PLETSCHER, JR., or Amuse-Innen, :unna snaren,swrznnLANn.

` AUTOMATIC. cnr-OUT rca iinnrrne cis-cuirs.

` Original` application filed `Demeniher 4, 1924, Serial -No.,?i3,820,and in Germany December Divided and` ausfapp11-eati mV flied apra 1,192e. semi No. 99,173.

.It 'has already frequently been attempted to construct socket devicesfor heating appa; ratus such as flat-irons, cooking apparatus etc.7which socket devicesfcontain an'au'tomatic cut-out which cuts oif thecurrent when the heating apparatus reachesa temperature which is toohigh and is dangerous for itself and its surroundings. These knownsocket devices with automatic cut-outs'forpprotece tion againstoverheating all suffer fron'itwo disadvantages, viz, that theynecessitate mak ing the socket device of `considerable magnitude and ofvery different size from that ofthe usual socketdevices and thatthetransmission of heat fromthe heating apparatus to the automatic switchisV very deficient andy very slow inasmuch Sas this transmission onlytakes place through the electrical conducting wire which naturally isonly or" small crosssection. i f i The subject of the presentfinventionis'za socketdevice for heating apparatus with an automatic cut-out f forprotection against overheating in which the above-mentioneddisadvantages are avoided inasmuch as the size of the socket device ishardly greater than the normal size of a standard socket device andinasmuch as the heat transmission takes place over a metalliccross-section which is not restricted tothe diameter of, the conductingwire. l

= These resultsare obtained by forming the socket which is to Vpass overthe contact pin or plug into a cup. at the end Vwhich lies with--V inthe socket, on which cup the fusible disc is pressed by means ofanvinsulating member which forms a. part of the socket device, wherebythe fusible disc retains in electrically and thermally conductivecontact a rodA carrying the current to the socket against the influence0f a .spring which acts on the rod, so that the fusible disc receivesheatA over `its whole surface. i v

The drawing shows by way of example two constructional forms of theinvention.V

Figs. l and 2 show the first constructional form in axial section in thein and out positions respectively.

Fig. 3 shows the second constructional form in axial section.

A case or housing consists of an enclosing member made in three partsand constructed of insulating material. The middle part of the said caseforms a holder 29, to which at the one end the socket connecting member30 and at the other end a closing cap 3l Vare screwedby means of ameta-l tube 32, which tube 32 is arranged inthe axial hole of thevholder 29. The upper end part of the `tube 32 is adapted to form theterminal 33 for the conductor 34 which passes through theIcap 3l*` andis protected by being constructed in Y the form of a cable. In the holeof the holder 29 a metal ring member 37 is fixed, whichv ring memberrests on va*` ledge 36. The ring member 37 is provided with a rod 38which maintains good connectionfor' the electric current andghas ahead-39 andl40'respectively at each Vof its two ends. kA helicalspring 4l isarranged around the rod 38 between ,the disc37andfthe head 39, whereby afusible disc42 fixed at the lower end of the. rod 38 is `pressed by `thehead 40V against the lower nally slotted socket 43 `with a eontactplate44 is inserted in the socket connectingvvmember 3.0, the said slottedsocket 43vbeingso dimensioned that when the device is screwed uptheplate 44 presses Iagainst the under surface" of the fusible disc 4,2`and-the hea-d 40 rests in a hollow in the contact plate/44. By tightlyscrewing the parts 29 and" 30 together a good electrically and thermallyconductive connection is obtained, whilstpwhen the'fusible disc ismelted, the melted mass is enabled to penetrate into an open spaceand 2)which springs back in the hole in the holder 29 under the influence ofthe spring 41.` If it be desired to insert a new fusible disc theclosing'cap 31 with the tube 32 on the one side and the socketconnecting member 30 on the other side are first unscrewed from theholder 29 and the melted mass is removed from the contact plate 44. Therod 38 is then pressed forward, a new fusible disc 42 is placed on thesame and the whole device is screwed together again.

Fig. .8 also shows a socket device for flatirons, in which device aholder 47 is screwed Vend `surface/of the holder 29. vA longitudif l filon to the socket connecting member 46. In

is arranged. The said rod is arranged in a centrally bored metal disc 51which, for example, may be pressed into a widened portion of the'hole inthe holder. An insulation head 52 is screwed on to therod 50.- A helicalspring 53 arranged on the rod 50 presses against the head 52 and isadapted to effect the movement of the rod when the fusible material ismelted. Vhen'this occurs the head 52 projects out of the holder 47 andthus indicates the destruction of the fusible material. more noticeablethe said head 52 may be of a dierent colourfrom the holder 47. Theholder is provided with a side armor projectio1r54. A terminal 55 whichpresses against the disc and is thus in conductive contact with it isprovided and an insulating protecting'cover 56k is screwed over the saidterminal 55.A

The rod 50 may be arranged on a continuation of the `terminal 55, saidcontinuation projecting into the hole 48. It is also intended that thiscut-out may be constructed in a double pole type, in which caseusuallyonly the one -pole would be protected against excesstemperature as thefuse member is not dependent -on or adjusted' to the current strength. fx

Iclaim: I y LSocketdevice for heating or heat developing apparatus withautomatic switch for protection against overheating, in combination witha socket, the interior of which is formedinto a cup vat the. oppositeend to that which passes over a contact-pin or plug, a fusible discpressed by meansof an insulating member which formsV part of the socketdevice V0n said curp, the lower end of the insulating member and the rimof vthe cup being 'b'evelled off in sucha way that aV chamber runningcircularly round the eX- terior edge of the fusible disc is formed intowhich the melted matter iows when the fuse blows, a rod carrying thelcurrent to said socket, a spring acting on said rod so as to In. orderto render the indication lift the rod from thev cup, a metal ring, on

which ring the spring rests, the` rod being arranged in an electricallyconductive manner in said metal ring, the ring Vbeing held in' itsposition for theproper guiding of the rod by means of a metal tubeconnected with the wire carrying the; current, said fusible discretaining the rod in electrically and thermally conductive contact withthe socket and receiving heat over its whole under surface.

2. Socket device for heating or heat developing apparatus with automaticswitch for'protection against overheating, in combination a housingconsisting of anv enclosing member made in three'parts andA constructedof insulating material, the middle part of said housing forming a holderto which at theo-ne end a socket-connectingmember and at the other endaclosing cap are screwed, the latter by `means' of a metal tube, saidtube being arranged inthe axial hole of the holder, the upper end partof the tubebeing adapted' to form the terminal for a conductor passingthrough the cap, a metal ring member provided with a rod which maintainsgood connection for the electric current and having a head at each ofits two ends, a helical spring arranged around the rod between-the metalring member and the one head of the rod, a fusible disc fixed atthelower end of the rod and being pressed by the khead of the rod againstthe lower end surface of the holder, a longitudinally lslotted socketwith a contact plate inserted in the socket connecting member, the saidslotted socket being so dimensioned that when the device is screwed upthe plate of the'longitudinally slotted socket presses against the undersurface of the fusible disc and the head rests in a hollow in thecontact 'plate of the longitudinally slotted socket, substantially asdescribed.

In testimony whereof I have signed my name to this specification.

OTTO PLETSCHER, JUN.

